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SPC MD 409

Mesoscale Discussion 0409
NWS Storm Prediction Center Norman OK
1254 PM CDT Mon May 14 2018
Areas affected...Portions of western and northern Missouri and
eastern Kansas
Concerning...Severe potential...Severe Thunderstorm Watch likely
Valid 141754Z - 141930Z
Probability of Watch Issuance...95 percent
SUMMARY...Thunderstorms are expected to develop along and south of a
quasi-stationary front between 18 and 19z. Severe wind gusts and
marginally severe hail are the main threats. Watch issuance is
likely.
DISCUSSION...Quickly-eroding convective inhibition, a weak frontal
wave/MCV over the Kansas City area, and frontal convergence over
Kansas is expected to contribute to scattered thunderstorm
development in the next hour or two. Over Missouri, effective bulk
wind shear is rather small and will gradually decrease even further
through the afternoon to values of 15-25 kt. Effective bulk shear
will be slightly higher --25-35 kt-- over eastern Kansas. Multicells
will be the dominant mode, but MLCAPE of 2000-2500 J/kg and DCAPE
that is expected to rise to 1000-1200 J/kg will contribute to severe
wind potential in any of the stronger downdrafts, particularly with
the initial thunderstorms before outflow spreads rapidly over the
area.
Over Missouri, although severe hail is possible in any of the
stronger storms, a relative minimum in mid-level lapse rates and a
lack of organized storm rotation should keep hail sizes on the
marginally-severe end. Over Kansas slightly higher effective bulk
shear and larger lapse rates could produce somewhat larger hail over
the area. High-resolution guidance suggests outflow will quickly
consolidate into a mesoscale cold pool over both areas, but weak
vertical wind shear should preclude any organized MCS development
and thus preclude any organized, larger-scale severe wind potential.
But the coverage of storms and severe wind/hail potential is
expected to be large enough to need a Severe Thunderstorm Watch over
the area by 19z.
..Coniglio/Grams.. 05/14/2018
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LSX...DVN...SGF...EAX...TOP...ICT...
LAT...LON 38179223 38079283 37819481 37479671 37449729 37769748
38269704 39319566 39729458 39959405 40479324 40549229
40139163 39449130 38799140 38179223